The update will arrive this summer. However, Cortana on Xbox One will only available in the US, UK, France, Italy, Germany and Spain.

Microsoft stated:

Cortana is coming to Preview in the U.S., U.K., France, Italy, Germany and Spain first, and gamers can expect the familiar Cortana experience found on other Windows 10 devices. Cortana voice commands on Xbox One will work with both headsets and Kinect. You’ll be able to use Cortana to find great new games, see what your friends are up to, start a party, accomplish common tasks, turn on your Xbox One if you’re using Kinect, and more. We’ll continue to build Cortana features over time and our vision is to use Cortana to help elevate your experience as your personal digital assistant for gaming. Just say “Hey Cortana” or launch the app to get started!